Planetary atmospheres · climate dynamics · disequilibrium chemistry
Hi, I am Jiachen Liu.
I study climates and atmospheres beyond Earth, from hothouse terrestrial planets to the temperate mini-Neptune K2-18b.
I use 1D and 3D climate, chemistry, and radiative-transfer models to understand how planets look, evolve, and become observable.
K2-18b in 3D
Modeling atmospheric dynamics, chemical transport, and synthetic spectra to test what JWST can really tell us.
When Wetter Gets Weirder
Investigating why very hot terrestrial planets can break our simple expectations about precipitation and habitability.
From 1D to 3D
Connecting simple conceptual models with full atmospheric simulations, because planets rarely stay polite.
About Me
I am a PhD student at the Department of Atmospheric and Oceanic Sciences, Peking University. I was born and raised in Guangzhou, a megacity in South China.
I earned my bachelor’s degree from the School of Atmospheric Sciences at Sun Yat-sen University, where I first researched the effects of doubling CO2 on Earth’s temperature structure using a simple one-dimensional climate model. I started my PhD at Peking University in 2021, shifting my research focus from Earth to more general Earth-like terrestrial planets and their habitability.
From February 2024 to August 2025, I worked as a visiting student at the Department of Atmospheric Physics of Exoplanets at the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany. At MPIA, I changed my research focus to the temperate mini-Neptune K2-18b, investigating its chemistry and dynamics using both 1D and 3D forward models.
Research Coordinates
- Current orbit
- 3D disequilibrium chemistry in sub-Neptune atmospheres
- Favorite targets
- K2-18b, hothouse terrestrial planets, tidally locked worlds
- Favorite tools
- Climate models, chemical kinetics, radiative transfer, synthetic observations
- Scientific mood
- Curious, model-driven, and suspicious of overly simple interpretations
Recent Highlights
I successfully defended my thesis on 3D disequilibrium chemistry in sub-Neptune atmospheres. Congrats to Dr. Liu!
Part II of our K2-18b paper was accepted to MNRAS. The preprint version can be found here. We presented a detailed analysis of the 3D chemical structures on K2-18b, compared synthetic transmission spectra with JWST observations, and found that K2-18b's interior can be interpreted as a gas-rich mini-Neptune with ~180x solar metallicity.
A very busy month. I attended conferences in Guizhou, Beijing, and Shanghai, and also gave talks at Sun Yat-sen University.
I gave a BOWIE+ Seminar virtually.
I went back to Beijing to start the final year of my PhD.
I visited the University of Oxford and the University of Exeter and gave seminars.
A paper led by me was published in Monthly Notices of the Royal Astronomical Society. In this study, we perform 3D chemical kinetics simulations of sub-Neptune K2-18b. This is Part I of a series, examining atmospheric dynamics and their impact on the transport of passive tracers.
I gave a talk at Exoclimes VII and Exocoffee at MPIA.
A paper led by me was published in the Astrophysical Journal. In this study, we investigated the formation mechanism of the near-surface atmospheric inversion in hothouse climates.
I gave an invited talk at EGU 2025 and an invited virtual talk at the Climate Sensitivity Journal Club at GFDL.
A paper led by me was published in Science Advances. In our work, we show that the relation between surface temperature and precipitation reverses in very hot climates (>~320 K).
I did a PICO presentation on the reversal of precipitation trend in hot climates at EGU 2024.
I arrived at Heidelberg and started to work on a "real" exoplanet, K2-18b.
A paper involving me as a collaborator was published in Nature Astronomy. In this work, we used a cloud-permitting model to simulate explicit convection on 1:1 tidally locked rocky planets orbiting low-mass stars.
I gave an oral presentation on the effects of surface gravity at EGU 2023.
My first first-author paper was published in the Astrophysical Journal. In this work, we investigated how surface gravity affects water clouds, planetary climate, and transmission spectra.
A paper involving me was published in Geophysical Research Letters. In this work, we demonstrated that precipitation is weaker when atmospheric mass is larger for a given surface temperature.
Started my PhD!